Method of moistureproofing wrapping materials



Patented June 21, 1938 PATENT OFFICE.

METHOD or MOISTUREPROOFING WRAP- rmc MATERIALS Ralph T. K. Oornwell,Fredericksburg, Va... as-

signor to Sylvania Industrial Corporation,

Fredericksburg, Va.,

a corporation of Virginia No Drawing. Application January 29, 1936,

Serial No. 61,313

18 Claims.

The invention relates in general to a moistureproofingv composition andto materials coated therewith. More particularly it relates to awrapping material coated with such a composition which is therebyadapted for use in wrapping moisture-containing]products, and tocorrelated improvements whereby the sealing of such wrapping materialsis enhanced through the use of a solvent.

There are now in common use a number of non-fibrous cellulosic wrappingmaterials, some of which are coated with a moistureproofingcompositionfor the purpose of rendering them suitable for wrappingfoodstufis, drugs, tobacco products and the like. When very moist or wetmaterials such as butter, cheese, meat and the like are packed in suchmoistureproof wrapping materials, the moistureproof coating frequentlybecomes loosened from the base and may become so detached with theresult that the utility of the package is seriously impaired. It hasbeen proposed to increase the adherence of the moistureproof coating tothe base sheet material through the use of an intermediate waterproofcoating disposed between the moistureproof coating and the base. The useof an intermediate coating requires a double coating operation,expensive solvent mixtures and greatly increases the cost,

of the wrapping material. 30 Heretofore, it has been proposed to sealmoistureproofed wrapping materials by heat and pressure, in which casethe efiectiveness of the seal depends upon the heat-fusible ingredientsof the molstureproofing composition. The seals produced by heat andpressure alone are, however, lacking in strength and tenacity so thatsuch seals are suitable only where there is no substantial strain. Ithas been proposed, also, to seal moistureproofed wrapping materials by asolvent for the coating, and preferably with heat and pressure. With themoistureproofing compositions heretofore available, the use of a solventwas objectionable in that, instead of rendering the coating compositionadhesive, the solvent partially 45 dissolved the coating and loosened itfrom the base without providing an efiective seal. It has been foundthat the strength of a seal produced by the action of a solvent upon themoistureproofing composition depends in a large measure 50 upon thenature and amount of the several ingredients present in the composition.

It is a general object of the present invention to provide atransparent, moistureprooi coating composition which, when applied to asuitable 55 base, will enable the contiguous surfaces of the coated baseto be sealed by means of a solvent to provide a strong permanent sealwithout detractlng from the transparency or moistureproofness of thecoating.

Another object of the invention is to provide a wrapping material havinga moistureproof coating thereon which will enable the contiguouscoatedsurfaces to be sealed together by means of a solvent and pressure andwhich coating is strongly adherent to the base in the presence of liquidwater for a substantial period of time.

It is a further object of the invention to incorporate in a coatingcomposition comprising a lacquer base and a wax, a plasticizing resinwhich is odorless, substantially colorless, light stable and soluble inlacquer base solvents.

It is a specific object of the invention to provide a novel coatingcomposition adapted for coating sheets and films formed of a hydrophiliccolloid, the coating being transparent, moistureproof, non-tacky andstrongly adherent to the base and capable of providing a strongpermanent seal o f contiguous coated surfaces by the use of solvent andpressure.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The coating composition of the present invention comprises in general'acompatible mixture of a, lacquer base, a wax, a wax-blending agent, aresin formed by combining an alkyd resin and an aromaticsulphonamide-aldehyde resin and a suitable solvent mixture therefor(said resin will hereinafter be referred to as a plasticizing resin).

To this mixture may be added a. plasticizer, a pigment, a dye and/orother lacquer ingredients.

The invention accordingly comprises novel products possessing thecharacteristics, properties, elements and the relation of elements allas exemplified in the following detailed disclosure and the scope of theapplication of which will be indicated in the claims.

By way of illustration, but not by way of limiting the invention, it maybe stated that the several ingredients may be present in the compositionafter evaporation of solvent in the following general proportion:

Percent Lacquer base from 40 to 65 Plasticizing resin from to 35Plasticizer from 5 to Wax from 0.5 to '7 Non-volatile wax blending agentfrom 0.5 to

For the lacquer base there may be employed a linseed, soya bean,perilla, etc.

suitable cellulose derivative such, for example, as nitrocellulose,cellulose acetate, ethyl cellulose,

benzyl cellulose or a film-forming synthetic resin in that it hassubstantially no film-forming properties when used alone.

The plasticizing resin used in the invention may be produced as abovestated. The alkyd resin is made by reacting a polyhydric alcohol such,for example, as glycol or glycerol with a polycarboxylic acid such, forexample, as maleic acid or phthalic acid. The alkyd resin is combined orreacted with an aromatic sulphonamide-aldehyde resin formed by thecondensation of an arcmatic sulphonamide, as benzene sulphonamide, withan aldehyde, for example, formaldehyde. The product resulting from thecondensation of the two resins is a viscous liquid or soft solid, whichis characterized by being light in color, substantially transparent,odorless, water-repelling, substantially' light-stable, soluble incommon lacquer solvents, and'which functions to improve the flexibilityof coatings and films produced from compositions containing it. A moreimportant feature of the plasticizing resin is that it renders thecoatings or films solvent-scalable with a like film to produce a jointwhich is stronger than a similar joint produced when said films areheat-sealed and stronger than a joint produced with the same solvent onfilms formed from the same composition omitting the plasticizing resin.

As a plasticizer there may be used either per se or in combinationethoxy ethyl phthalate, dibutyl phthalate, triphenyii phosphate, butylbenaoyl benzoate and the like.

Any suitable animal, mineral or vegetable wax may be used to impartmoistureproofness to the composition, but in the preferred embodiment ofthe invention there is used paramn wax having a high melting point.

The non-volatile wax blending agent may be a blown oil and/orv a gum orresin Either a blown or boiled oil of animal or vegetable origin may beemployed, for example, rapeseed, neats-foot, The gum or resin used as awax-blending agent may be of the type of wax-free dammar or an estergum; also phthalates of hydroxy fatty acids and other materials whichare characterized by having a low melting point and a solubility both inhydrocarbon and in oxygen-containing solvents used in the lacquers maybe utilized. In the preferred embodiment, the wax-blending agentcontains a blown oil and a resin.

By way of more specific illustration of an improved moistureproofingcomposition embodying my invention, I mention the following examples inwhich all ingredients, except the solvents'are expressed in parts byweight:

No. 1 No. 2

Nitrocellulose (H see). Plasticizing resin Di-butyl phthalate lParaffin, M. P. 67 C. 5 Dammar gum Ester gum Blown rapeseed Oil Alacquer may be prepared by taking up about parts of one of the abovecompositions in the usual way,

' tionof solvent are transparent, non-greasy, nontacky, substantiallyodorless and highly moistureproof.

Further the compositions are especially adapted for coating wrappingmaterials formed of organic hydrophilic colloids such, for example, ascellulose hydrate, alkali-soluble cellulose ethers, gelatin, casein andthe like. On such materials, the coating eifectively prevents thediffusion of water vapor through the material and, at the same time,shows a high waterproofness and strong adherence to the base in thepresence of liquid water. As a result of these characteristics, awrapping material comprising a sheet of a hydrophilic colloid and coatedwith the moistureproofing composition of the invention is especiallyadapted for wrapping various types of moisture-containing goods, forexample, foodstuffs as meat, butter, cheese, as well as drugs, tobaccoand the like.

I have found that if a film or sheet of glycerinated regeneratedcellulose having a thickness of about one-thousandth of an inch becoated, preferably on each side, with a moistureproofing composition ofapproximately 1.5 ten thousandth of an inch total thickness prepared inaccordance with the present invention, theresistance of the coated sheetto the diffusion of water vapor is at least 50 times as great as that ofthe uncoated sheet of glycerinated regenerated cellulose when both aretested comparatively at ordinary temperatures up to 38 or 40 C. The termmoistureproof as used herein is intended to cover a composition havingsuch a moisture proofing value when so tested.

Another outstanding characteristic of the wrapping materials coated withthe moistureproofing composition of the invention is that the contiguoussurfaces may be eifectively sealed together by the application of asolvent sealing agent such as methyl Cellosolve, methyl acetate,acetone, etc. When a small amount of the solvent is applied to thecontiguous, coated surfaces and the surfaces pressed together,preferably with the application of heat, there is produced, afterevaporation of the sealing solvent, a strong tenacious seal withoutimpairing the transparency, flexibility or moistureproofness of thecoating. The seal so produced is materially stronger than a seal of thesame dimensions produced by heatsealing analogous, moistureproof,transparent coatings of the same thicknes when applied to the same basesheet material.

Since certain changes may be madev in the above composition of matterand article produced utilizing the same, and different embodiments ofthe invention could be made without departing from the scope thereof, itis intended that all matter contained in the above description shall beinterpreted asillustrative and not in a limiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindea plasticizing resin resulting'irom the condensation of an alkyd resinwith a sulphonamidealdehyde resin.

2. A moistureproofing' composition comprising a lacquer base, a wax, awax-blending agent, a plasticizing resin resulting 'fromthe condensationof an alkyd resin with a sulphonamide-aldehyde resin and a solvent, saidingredients being I present in such proportions as to deposit, uponevaporation of solvent; a transparent, moistureproof film which issolvent-scalable with a like film to produce a joint which is strongerthan a similar joint produced when said films are heat-- sealed.

3. A moistureproofing composition comprising a lacquer base, a wax, awax-blending agent, a plasticizing resin resulting from the condensationof an alkyd resin with a s'ulphonamide-aldehyde resin, a plasticizer anda solvent, said ingredients being present in such proportions as todeposit, upon evaporation of solvent, a flexible, transparent,moistureproof film which is solventscalable with a like film to producea joint which is stronger than a similar joint produced when said filmsare heat-sealed.

4. A moistureproofing compositioncomprising a lacquer base resin, a wax,a wax-blending agent, a plasticizing resin resulting from thecondensation of an alkyd resin with a sulphonamide-aldehyderesin, aplasticizer and a solvent, said ingredients being present in suchproportions as to deposit, upon evaporation of solvent, a flexible,transparent, moistureproof film which is solventsealable with a likefilm to produce a joint which is stronger than a similar joint producedwhen said films are heat-sealed.

5. A moistureproofing composition comprising a cellulose derivative, awax, a wax-blending agent, a plasticizing resin resulting from thecondensation of an alkyd resin with a sulphonamidealdehyde resin, aplasticizer and a solvent, said ingredients being present in suchproportions as to deposit, upon evaporation of solvent, a flexible,transparent, moistureproof film which is solvent-sealable with a likefilm to produce a joint which is-stronger than a similar joint producedwhen said films are heat-sealed.

6. A moistureproofing composition comprising nitro-cellulose, a wax, awax-blending agent containing a blown oil and a gum, a plasticizingresin resulting from the condensation of an alkyd resin with asulphonamide-aldehyde resin, a plasticizer and a solvent, saidingredients being present in such proportions as to deposit, uponevaporation of solvent, a flexible, transparent, moistureproof filmwhich is solvent-sealable with a like film to produce a joint which isstronger than a. similar joint produced when said films are heat-sealed.

7. A moistureproofing composition comprising 40% to 65% of a lacquerbase, 0.5% to 7% of a wax, 0.5% to 30% of a wax-blending agent, 5% to ofa plasticizing resin resulting from the condensation of an alkyd resinwith a sulphonamide-aldehyde resin, 5% to 10% of a plasticizer and asolvent, said ingredients being present in such proportions as todeposit, upon evaporation of solvent, a flexible, transparent,moistureproof film which is solvent-scalable with a like film to producea joint which is stronger than asimilar joint produced when said filmsare heat-sealed.

8. A moistureproofing composition comprising to 65% of. nitrocellulose,0.5% to 1% of paraflin wax, 0.5% to 30% of a wax-blending agentcontaining a blown oil .and a sum, 5% to 35% of a plasticizing resinresulting from the condensation of an alkyd resin with asulphonamide-aldehyde resin, 5% to 10% of a plasticizer and a, solventmixture, said ingredients being present in such proportions as todeposit, upon evaporation of solvent, afiexible, transparent,

moistureproof film which is solvent-scalable with a like film to producea joint which is stronger than a 'similar joint produced when said filmsare heat-sealed.

9. As an article of manufacture, a non-fibrous organic hydrophiliccolloid material having a mo'istureproof coatingcomprising a lacquerbase, a wax, a wax-blending agent and a plasticizing resin resultingfrom the condensation of an alkyd resin'with a sulphonamide-aldehyderesin, said coating being solvent-scalable with a like coating toproduce a joint which is stronger than a simi-' lar joint produced whensaid coatings are heatsealed.

10. As an article of manufacture, a non-fibrous cellulosic materialhaving a moistureproof coating comprising a lacquer base, a wax, awaxblending agent, a plasticizing resin resulting from the condensationof an alkyd resin with a sulphonamide-aldehyde resin, and a plasticizer,said coating being solvent-scalable with a like coating to produce ajoint which is stronger than a similar joint produced when said coatingsare heatsealed.

11. As an article of manufacture, regenerated cellulose having amoistureproof coating comprising a lacquer base, a wax, a wax-blendingagent, a plasticizing resin resulting from the condensation of an alkydresin with a sulphonamidealdehyde resin, and a plasticizer, said coatingbeing solvent-scalable with a like coating to produce a joint which isstronger than a similar jointv produced when said coatings areheatsealed.

12. As an article of manufacture, a wrapping material having a,moistureproof coating comprising a lacquer base, a wax, a wax-blendingagent and a plasticizing resin resulting from the condensation of analkyd resin with a sulphonamidealdehyde resin, said coating beingsolvent-sealable with a like coating to produce a joint which isstronger than a similar joint produced when said coatings areheat-sealed.

13. As an article of manufacture, a wrapping material comprising atransparent sheet of nonfibrous, cellulosic material having amoistureproof coating comprising a lacquer base, a wax, a waxblendingagent, a plasticizing resin resulting from the condensation of an alkydresin with a sulphonamide-aldehyde resin, and a plasticizer, saidcoating being solvent-sealable with a like coating to produce a jointwhich is stronger than a similar joint produced when said coatings areheat-sealed.

14. As an article of manufacture, a wrapping material comprising atransparent sheet of regenerated cellulose having a moistureproofcoating comprising a lacquer base, a wax, a wax- All joint producedwhensaid coatings are heatsealed 15. material comprising a, transparentsheet of nonfibrous, organic hydrophiliccolloid material having amoistureprootcoating comprising a cellulose derivative, a wax, awax-blending agent, a plasticizing resin resulting from the condensationof an alkyd resin with a sulphonamide-aldehyde resin, and a plasticizer,said coating being solventseaiable with a like coating to producea'joint which is stronger than a similar joint produced when saidcoatings are heat-sealed.

16. As an article of manufacture, a wrapping material comprising atransparent sheet of regenerated cellulose having. a thin moistureproofcoating comprising nitrocellulose, a wax, a waxblending agent containinga blown oil and a gum, a plasticizing resin resulting from thecondensation of an alkvd resin with a sulphonamidealdehyde resin, and aplasticizer, said coating being solvent-sealable with alike coating toproduce a joint which is stronger than a similar joint produced whensaid coatings are heatsealed.

17. As an article of manufacture, a wrapping As an article ofmanufacture, a wrapping material comprising a, transparent sheet'ofregenerated cellulose having a thin moistureproot coatingcomprising 40%to 65% of a'lacquerbase,-

0.5% to 7% of a wax, 0.5% to 30% of a waxblending agent, 5% to 35.% of aplasticizing resin resulting from the condensation of an alkyd resinwith a sulphonamide-aldehyde resin, and 5% to of a plasticizer, saidcoating being solventsealable with a like coating to produce a jointwhich is stronger than a similar joint produced when said coatings areheat-sealed.

18. As an article of manufacture, a wrapping material comprising atransparent sheet of regenerated cellulosehaving a thin moistureprooicoating comprising 40% to 65% oi'-'nitrocellulose, 0.5% to 7% of paramnwax, 0.5% to 30% of a wax-blending agent containing a blown oil and agum, 5% to 35% of a plasticizing resin resulting from the condensationof an alkyd resin with a sulphonamide-aldehyde resin, and 5% to 10% ofplasticizer, said coating being solvent-sealable with a like coating toproduce a joint which is stronger than a similar joint when saidcoatings are heat-sealed.

RALPH T. K. CORNWELL.

